The present invention relates generally to the field of scanners and other devices used for transforming an optical image of a document into an electronic signal and more particularly to an integrated automatic document feeder and active transparency adapter for a scanner.
Electronic document scanners, copiers, and facsimile machines transform an optical image of a document, photograph or transparency into an electronic signal suitable for storing, displaying, printing, processing by a computer or electronic transmission. A document scanner may be a separate device or a document scanner may be a part of a copier, part of a facsimile machine or part of a multipurpose device. For opaque documents, reflective scanners typically have a controlled light source which is reflected off of the surface of a document, through an optics system, and onto an array of photosensitive devices. The photosensitive devices convert received light intensity into an electronic signal. Transparency scanners pass light through a transparent image, for example a photographic positive slide, through an optics system, and then onto an array of photosensitive devices.
A transparent image may be scanned in a reflective scanner by placing a white surface behind the transparency. In such an arrangement, light passes through the transparency to the white background, reflects off the white background and passes through the transparency a second time before impinging onto the photosensitive devices. Therefore, light is filtered twice by the transparent image. In general, this double filtering creates an unacceptable distortion of gray scale, color, contrast and other image characteristics of interest.
Reflective flat bed document scanners may be adapted to scan transparent images by providing a separate light source to back-light the image so that the light passes through the transparency only once. In some systems, separate mirrors, lens and other optics may be required to properly project the image onto the photosensitive devices. Motors may also be required to move the external light source relative to the image. One such method is to use cathode fluorescent light bulbs in the scanner lid, so that there is back lighting, rather than reflective lighting for scanning transparencies. This method creates a very large scanner lid, since the fluorescent light bulbs are typically xc2xd to 1xc2xd inches thick. This is also expensive in terms of additional components and requires a complex power supply to ensure that all of the lights are stable and the same brightness throughout the scanning process.
U.S. Pat. No. 5,463,217 (Sobol et al.), which is incorporated herein for all that it teaches and describes, describes a completely passive adapter for scanning transparent images in a reflective scanner without requiring a separate light source for back lighting. A light source in the reflective scanner provides light which passes outside the area of the transparent image. The adapter captures the light which passes outside the area of the transparent image and reflects the light through the transparent image. The reflected light re-enters the scanner along the optical path required by the scanner internal optics. The various embodiments described in Sobol et al. are suitable for a fixed scanner optical path. However, when a new scanner is developed, the angle of the adapted mirrors may need to change to accommodate a different optical path within the new scanner. The adapter of Sobol et al. requires an arrangement of mirrors, metal or a folded metallic coated cardboard adapter to be placed onto the platen glass. The adapter of Sobol et al. comprises at least one additional component to the scanner that may be misplaced or damaged. A similar transparency adapter is disclosed in U.S. Ser. No. 09/127,454 entitled Adjustable Adapter for Scanning Transparencies with a Reflective Document Scanner by Patrick Batten et al., filed Jul. 31, 1998, which is also incorporated herein for all that is taught and disclosed. Neither of these methods permits a full size image to be scanned when a transparency is being scanned.
Another method in which reflective scanners have been adapted to scan transparent images by providing a light source and moveable mirrors in the lid of the scanner. U.S. Pat. No. 5,710,425 (McConica et al.), which is incorporated herein for all that it teaches and describes, describes a scanner with a light source and moveable mirrors in the lid of the scanner and two different light paths depending on whether the document to be scanned is opaque or transparent. The first light path would reflect off of an opaque document and the second would pass through a transparent document. The mirrors within the lid reflect light back into the base of the scanner or onto the document being scanned. The device of McConica et al. require many components to be installed within the lid of the scanner and also require two separate sets of optical components to support two different light paths. There are also moving parts within the lid, which may get out of alignment due to opening and closing of the lid as would be required under normal scanner use.
All of these solutions only deal with flatbed scanners. There is not a good solution for allowing the scanning of a transparent document by an automatic document feeder (ADF) scanner device. In the past, a simple automatic document feeder permitted the scanning of multiple documents. When the ADF was attached to a flatbed scanner, the end user could scan flat originals as well, but to use a transparency adapter, the end user had to disable the ADF and changer over to the transparency adapter. The end user also had to turn off the scanner and reboot the computer to change from ADF capability to transparency adapter capability.
Moreover, most scanner accessories are sold separately and must be installed onto the scanner one at a time by the end user. This is troublesome because the electrical connector on the back of the scanner must be turned off to change an accessory. Sometimes it is also necessary to reboot the host computer so that the added accessory will be recognized by the computer or the scanner. An integrated automatic document scanner and active transparency adapter unit would enable the end user to scan flat documents, transparencies and automatic document feed input bundles without making any changes to their scanner configuration or setup.
One possible solution may utilize an accessory type active transparency adapter with a scanner having an automatic document feeder attached to the scanner, if the scanner is not used to control the active transparency adapter. This would be a relatively easy solution, but does not give the image quality required for transparent originals. For best image quality of transparent originals, the scanner should turn off the internal scanner light and utilize the active transparency light when scanning transparent documents. The scanner should also calibrate using the active transparency adapter light, so active transparency adapter accessories without scanner control will necessarily not result in high quality transparent images. Accordingly, an active transparency adapter accessory is not considered to be a very good solution to the problem of trying to use an automatic document feeder scanner to scan transparent documents.
It would be desirable to have an integrated automatic document feeder and active transparency adapter, but does not add significantly to the component count or cost of the scanner, does not add significantly to the manufacturing cost, does not add significantly to the overall height, size or weight of the scanner, does not add moving parts to the scanner that may get out of alignment due to mechanical jarring, and does not significantly increase the complexity of the scanner or the power supply of the scanner.
The above and other aspects of the present invention are accomplished in a scanner that utilizes an integrated automatic document feeder and active transparency adapter in order to permit a scanner with an automatic document feeder capability to also scan transparent documents with minimal scanner down time and minimal requirements for the end user to reconfigure the scanner and computer between automatic document feed scans and transparent document scans. The solution would utilize a flat panel illuminator in the scanner lid in order to provide back lighting when a transparency is being scanned. The flat panel illuminator active transparency adapter could be mounted under the paper tray or platen area of the automatic document feeder unit. The flat panel illuminator active transparency adapter unit may be controlled using the same control cable used by the automatic document feeder unit. When the integrated automatic document feeder and active transparency adapter unit is installed onto the scanner, the end user can scan using the automatic document feeder mode, the active transparency adapter mode, or the flat platen area of the scanner.
The advantages of the present invention would provide one accessory that provides a complete scanning solution. The scanner would have automatic document feeder and active transparency adapter capabilities at the same time. Also, there would be no need to shutdown, reconnect or reboot the scanner or the computer to change accessories or scanning modes.